Physics & Astronomy Colloquium

New Views of Particle Acceleration with the Fermi Gamma-ray Space Telescope

Abstract: Extreme regions within our Galaxy and beyond it host nature's most powerful particle accelerators. The gamma radiation produced by electrons and ions accelerated to high energies contains answers to fundamental questions about where and how particle acceleration occurs. Although ideas about the origin of accelerated particles and the mechanism by which they gain energy have been around for some time, current telescopes are only now obtaining data that can confirm those ideas. Observations using the Fermi Gamma-ray Space Telescope have provided the first unmistakeable signatures of accelerated protons in several Galactic supernova remnants. The growing sample of gamma-ray remnants now provides new opportunities to answer important remaining questions about acceleration processes in the broader remnant population. In addition, Fermi observations have revealed surprisingly energetic gamma-ray outbursts that indicate that acceleration is happening in ways and in places that were not anticipated. Extremely rapid and energetic flares from the Crab Nebula defy the most common mechanism for accelerating particles to high energies. Unexpected detections of novae in gamma rays require an explanation for how such high energies may be reached in environments that were not previously considered favorable. As Fermi observations continue, we gain an ever deeper understanding of particle acceleration through the rich range of phenomena available in the Universe.

Bio Sketch: Elizabeth Hays is an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. She currently serves as a Deputy Project Scientist for the Fermi Gamma-ray Space Telescope, which has been operating since 2008. Elizabeth has enjoyed the rare opportunity to work throughout the gamma-ray portion of the electromagnetic spectrum on a variety of increasingly sophisticated gamma-ray telescopes. Her graduate studies at the University of Maryland using Milagro and later postdoctoral work on VERITAS at the University of Chicago fused her interests in identifying and characterizing particle accelerators through gamma-ray emission with the use of transients and flaring sources to advance the knowledge of astrophysical processes.

Refreshments will be served afterward in the PandA café on the 1st floor of Kinard Lab.